Bondable flame-retardant vanillin-derived molecules

ABSTRACT

A flame-retardant vanillin-derived molecule, a process for forming a flame-retardant resin, and an article of manufacture comprising a material that contains the flame-retardant vanillin-derived molecule are disclosed. The flame-retardant vanillin-derived molecule can be synthesized from vanillin obtained from a bio-based source, and can have at least one phosphoryl or phosphonyl moiety with phenyl, allyl, epoxide, propylene carbonate, or thioether substituents. The process for forming the flame-retardant resin can include reacting a vanillin derivative and a flame-retardant phosphorus-based molecule to form the flame-retardant vanillin-derived molecule, and binding the flame-retardant vanillin-derived molecule to a resin. The flame-retardant vanillin-derived molecules can also be bound to polymers. The material in the article of manufacture can be flame-retardant, and contain the flame-retardant vanillin-derived molecules. Examples of materials that can be in the article of manufacture can include resins, plastics, adhesives, polymers, etc.

BACKGROUND

The present disclosure relates to bio-renewable flame-retardantcompounds and, more specifically, resin-bondable flame-retardantvanillin-derived molecules.

Bio-based compounds provide a source of renewable materials for variousindustrial applications, such as polymers, flame retardants,cross-linkers, etc. One example of a bio-based compound that can be usedin these applications is vanillin (4-hydroxy-3-methoxybenzaldehyde).Vanillin is a plant metabolite and the main component of natural vanillaextract. While vanillin can be obtained from vanilla extract, orsynthesized from petroleum-based raw materials, a number ofbiotechnology processes are also used to produce vanillin. Theseprocesses can be plant-based or microorganism-based, and provide arenewable source of vanillin on an industrial scale.

SUMMARY

Various embodiments are directed to flame-retardant vanillin-derivedmolecules. The flame-retardant vanillin-derived molecules can have atleast one phosphoryl or phosphonyl moiety. Each phosphoryl or phosphonylmoiety can have at least one substituent selected from a groupconsisting of a phenyl substituent, an allyl substituent, an epoxidesubstituent, a propylene carbonate substituent, and a thioethersubstituent. The thioether substituent can be a hydroxyl-functionalizedthioether substituent, an amino-functionalized thioether substituent, ora carboxylic acid-functionalized thioether substituent. Theflame-retardant vanillin-derived molecules can be synthesized fromvanillin obtained from a bio-based source. Additional embodiments aredirected to forming a flame-retardant resin. The resin can be producedby forming a vanillin derivative, forming a phosphorus-basedflame-retardant molecule, and reacting the vanillin derivative and thephosphorus-based flame-retardant molecule with one another to form aflame-retardant vanillin-derived molecule. The flame-retardantvanillin-derived molecule can then be bound to a resin, forming theflame-retardant resin. The vanillin derivative can be a phenol vanillinderivative, a carboxylic acid vanillin derivative, or a benzyl alcoholvanillin derivative. The phosphorus-based flame-retardant molecule canbe a phosphate-based molecule or a phosphonate-based molecule with atleast one phenyl substituent, allyl substituent, epoxide substituent,propylene carbonate substituent, or thioether substituent. Furtherembodiments are directed to an article of manufacture comprising amaterial that contains the flame-retardant vanillin-derived molecule.The material can be a resin, plastic, adhesive, polymer, etc. Examplesof polymer materials can include polyurethane, an epoxy, apolyhydroxyurethane, a polycarbonate, a polyester, a polyacrylate, apolyimide, a polyamide, a polyurea, and a poly(vinyl-ester).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram illustrating a process of forming aflame-retardant polymer containing a flame-retardant vanillin-derivedmolecule, according to embodiments of the present disclosure.

FIG. 2A is a chemical reaction diagram illustrating processes ofsynthesizing three flame-retardant vanillin derivatives, according toembodiments of the present disclosure.

FIG. 2B is a diagrammatic representation of the molecular structures ofgeneric phosphorus-based flame-retardant molecules, according toembodiments of the present disclosure.

FIG. 3A is a chemical reaction diagram illustrating two processes ofsynthesizing the phosphate-based flame-retardant molecule, according toembodiments of the present disclosure.

FIG. 3B is a chemical reaction diagram illustrating two processes ofsynthesizing the phosphonate-based flame-retardant molecule, accordingto embodiments of the present disclosure.

FIG. 3C is a diagrammatic representation of the molecular structures ofthree thiol molecules that are involved in the synthesis of theflame-retardant vanillin-derived molecules, according to someembodiments of the present disclosure.

FIG. 4A is a chemical reaction diagram illustrating a process ofsynthesizing a functionalized flame-retardant phenol vanillin-derivedmolecule, according to some embodiments of the present disclosure.

FIG. 4B is a chemical reaction diagram illustrating three processes ofsynthesizing thioether-linked flame-retardant phenol vanillin-derivedmolecules, according to some embodiments of the present disclosure.

FIG. 4C is a chemical reaction diagram illustrating a process ofsynthesizing a propylene carbonate-functionalized flame-retardant phenolvanillin-derived molecule, according to some embodiments of the presentdisclosure.

FIG. 4D is a chemical reaction diagram illustrating a process ofsynthesizing a functionalized flame-retardant carboxylic acidvanillin-derived molecule, according to some embodiments of the presentdisclosure.

FIG. 4E is a chemical reaction diagram illustrating three processes ofsynthesizing thioether-linked flame-retardant carboxylic acidvanillin-derived molecules, according to some embodiments of the presentdisclosure.

FIG. 4F is a chemical reaction diagram illustrating a process ofsynthesizing a propylene carbonate-functionalized flame-retardantcarboxylic acid vanillin-derived molecule, according to some embodimentsof the present disclosure.

FIG. 4G is a chemical reaction diagram illustrating a process ofsynthesizing a functionalized flame-retardant benzyl alcoholvanillin-derived molecule, according to some embodiments of the presentdisclosure.

FIG. 4H is a chemical reaction diagram illustrating three processes ofsynthesizing thioether-linked flame-retardant benzyl alcoholvanillin-derived molecules, according to some embodiments of the presentdisclosure.

FIG. 4I is a chemical reaction diagram illustrating a process ofsynthesizing a propylene carbonate-functionalized flame-retardant benzylalcohol vanillin-derived molecule, according to some embodiments of thepresent disclosure.

DETAILED DESCRIPTION

Bio-based compounds are increasingly being used in the synthesis ofsubstances that previously required petroleum-based raw materials. Onebenefit of bio-based compounds is that they are from renewableresources. Therefore, these compounds have applications in sustainable,or “green,” materials. Sustainable materials are becoming more and moreprevalent, due to the rising costs of fossil fuels and increasingenvironmental regulatory controls. Advances in biotechnology haveprovided numerous strategies for efficiently and inexpensively producingbio-based compounds on an industrial scale. Examples of these strategiesinclude plant-based or microorganism-based approaches. Plant-basedapproaches can involve obtaining a material directly from a plant, orgrowing plant tissues or cells that can produce bio-based compounds fromvarious substrates using their own biosynthetic pathways.Microorganism-based approaches involve using native or geneticallymodified fungi, yeast, or bacteria to produce a desired compound from astructurally similar substrate.

Examples of substances that can be produced from bio-based compounds caninclude polymers, flame retardants, cross-linkers, etc. In someexamples, bio-based polymers and petroleum-based polymers are blended toform a polymer composite. However, polymers can also be entirelybio-based, or produced from a combination of bio- and petroleum-basedmonomers. Bio-based compounds can also impart flame-retardant propertiesto bio- and petroleum-based polymers. For example, flame-retardantmonomers or cross-linkers can be incorporated into polymers.Additionally, flame-retardant molecules can be blended or chemicallyreacted with the polymers.

Vanillin (4-hydroxy-3-methoxybenzaldehyde) is one example of a bio-basedcompound that has applications as a component of various polymers,resins, and small molecules. Vanillin is a plant metabolite and the maincomponent of natural vanilla extract. It can be obtained from the plant-and microorganism-based bio-sources discussed above, or synthesized frompetroleum-based raw materials. According to some embodiments of thepresent disclosure, vanillin is used as a precursor for flame-retardantmolecules. These flame-retardant vanillin-derived molecules can be boundto polymers and resins by functional groups on flame-retardant moieties.

FIG. 1 is a flow diagram 100 illustrating a process of forming aflame-retardant polymer containing a flame-retardant vanillin-derivedmolecule 104, according to embodiments of the present disclosure.Process 100 begins with the formation of a phosphorus-basedflame-retardant molecule. This is illustrated at step 105. Thephosphorus-based flame-retardant molecule has either a phosphoryl or aphosphonyl moiety (collectively referred to as an FR group) with anattached R group. Examples of R groups that can be attached to the FRgroup can include phenyl substituents, epoxide substituents, allylsubstituents, propylene carbonate substituents, hydroxyl-functionalizedthioether substituents, amino-functionalized thioether substituents, andcarboxylic acid-functionalized thioether substituents. The syntheses andstructures of phosphorus-based flame-retardant molecules are discussedin greater detail with regard to FIGS. 2B-3B.

Process 100 continues with the formation of a flame-retardant vanillinderivative. This is illustrated at step 110. Each vanillin derivativehas a flame-retardant group and a hydroxyl group. The derivatives areformed by a reaction of vanillin with the phosphorus-basedflame-retardant molecule and a reaction that replaces vanillin'saldehyde functional group with a hydroxyl group. Examples of reactionsthat can convert the aldehyde group to a hydroxyl group can includeoxidation by sodium percarbonate, oxidation by potassium permanganate,and reduction by sodium borohydride. The structures and syntheses of thederivatives of vanillin are discussed in greater detail with regard toFIG. 2A.

The vanillin derivative and the phosphorus-based flame-retardantmolecule are chemically reacted in order to form a flame-retardantvanillin-derived molecule 104. This is illustrated at step 115. Theidentity of the M group on the flame-retardant vanillin-derived molecule104 is determined by the phosphorus-based flame-retardant molecule andthe vanillin derivative used in the reaction. The phosphorus-basedflame-retardant molecules react with hydroxyl groups on the vanillinderivatives synthesized in step 105 to provide the FR group with theattached R group. Examples of FR groups, as well as the syntheses andstructures of flame-retardant vanillin-derived molecules 104 arediscussed in greater detail with regard to FIGS. 4A-4I.

The flame-retardant vanillin-derived molecule 104 formed in step 115 ischemically reacted with a resin, forming a bond between theflame-retardant vanillin-derived molecules 104 and the resin. This isillustrated at step 120. The flame-retardant resins formed in step 120can be converted into flame-retardant polymers. Examples of thesepolymers can include epoxies, polyhydroxyurethanes, polycarbonates,polyesters, polyacrylates, polyimides, polyamides, polyureas,poly(vinyl-esters), etc. The materials for these polymers can come frompetroleum-based sources, bio-based sources, or a combination ofpetroleum- and bio-based sources. Further, in some embodiments, theflame-retardant vanillin-derived resin can be used in non-polymericapplications, such as varnishes and adhesives.

FIG. 2A is a chemical reaction diagram illustrating processes 200-1,200-2, and 200-3 of synthesizing three flame-retardant vanillinderivatives, according to embodiments of the present disclosure. Thethree vanillin derivatives are a phenol flame-retardant derivative 215,a carboxylic acid flame-retardant derivative 225, and a benzyl alcoholflame-retardant derivative 235. These vanillin derivatives areprecursors for the flame-retardant vanillin-derived molecules 104, asdescribed in greater detail with regard to FIGS. 4A, 4D, and 4G.

In process 200-1, the phenol flame-retardant derivative 215 of vanillinis produced. The first step in this reaction replaces vanillin'shydroxyl group with an FR group. The FR group is provided by a reactionbetween vanillin 205 and either diphenyl chlorophosphate (DPCPa) ordiphenylphosphinic chloride (DPCPo), as well as catalyticdimethylaminopyridine (DMAP). If the reaction is carried out with DPCPa,the phenol flame-retardant derivative 215 will have phosphoryl FRsubstituents, and, if the reaction is carried out with DPCPo, the phenolflame-retardant derivative 215 will have phosphonyl FR substituents.

In the second step in process 200-1, deionized water (H₂O) andtetrahydrofuran (THF) are added to the reaction. The resulting mixtureis degassed with an inert gas (e.g., argon or nitrogen). While agitatingthe mixture, sodium percarbonate (Na₂CO₃.1.5H₂O₂) is added until pH=3 isreached, thus quenching the reaction. After quenching the reaction, theTHF is evaporated, and the aqueous phase is extracted with ethylacetate. The organic phases are collected, washed with brine, and driedover anhydrous sodium sulfate (Na₂SO₄). The ethyl acetate is removedunder reduced pressure, yielding the isolated phenol flame-retardantderivative 215.

In process 200-2, the carboxylic acid flame-retardant derivative 225 ofvanillin is produced. The first step in this reaction replacesvanillin's hydroxyl group with an FR group, and is carried out undersubstantially the same conditions as the first step in process 200-1. Inthe second step, an acetone/H₂O solution of potassium permanganate(KMnO₄) is added to the reaction. The mixture is stirred forapproximately 1.5 hours at room temperature. A solution of sodiumbisulfite (NaHSO₃) in hydrochloric acid (HCl) is added to the resultingpurple mixture until the mixture is colorless. The mixture is extractedwith ethyl acetate, and the organic phases are collected, washed withbrine, and dried over anhydrous magnesium sulfate (MgSO₄). The ethylacetate is removed under reduced pressure, yielding the isolatedcarboxylic acid flame-retardant derivative 225.

In process 200-3, the benzyl alcohol flame-retardant derivative 235 isproduced. The first step in this reaction replaces vanillin's hydroxylgroup with an FR group, and is carried out under substantially the sameconditions as the first step in process 200-1. In the second step,sodium borohydride (NaBH₄) is added to a solution of vanillin 205 inanhydrous ether or tetrahydrofuran (THF). The mixture is stirred at roomtemperature under an inert gas (e.g., argon or nitrogen) forapproximately four hours. The mixture is then concentrated, and purifiedby column chromatography to give the benzyl alcohol flame-retardantderivative 235.

FIG. 2B is a diagrammatic representation of the molecular structures 202of generic phosphorus-based flame-retardant molecules 240, according toembodiments of the present disclosure. Each phosphorus-basedflame-retardant molecule 240 is either a phosphate-based flame-retardantmolecule 240-1 or a phosphonate-based flame-retardant molecule 240-2.Herein, phosphoryl and phosphonyl moieties are replaced by theabbreviation “FR” in order to simplify illustrations of the molecularstructures. Each phosphorus-based flame-retardant molecule 240 has aphenyl (Ph) substituent and an R group that can bind to a resin.

The identities of the R groups bound to the phosphorus-basedflame-retardant molecules 240 vary, and are discussed in greater detailwith respect to FIGS. 3A, 3B, and 4A-4I. Additionally, in someembodiments, the phenyl group is replaced by another alkyl substituent(e.g., methyl, ethyl, propyl, isopropyl, etc.). The syntheses of thephosphorus-based flame-retardant molecules 240 are discussed with regardto FIGS. 3A and 3B. The phosphorus-based flame-retardant molecules 240are reacted with the vanillin derivatives 215, 225, and 235 to formflame-retardant vanillin-derived molecules 104. These reactions arediscussed in greater detail with regard to FIGS. 4A, 4D, and 4G.

FIG. 3A is a chemical reaction diagram illustrating two processes 300-1and 300-2 of synthesizing the phosphate-based flame-retardant molecule240-1, according to embodiments of the present disclosure. In bothprocesses 300-1 and 300-2, an alcohol 305 is a starting material for thephosphate-based flame-retardant molecule 240-1. The alcohol 305 haseither an allyl R group 307 or an epoxide R group 308. It should benoted that, though an allyl group 307 with a single methylene spacergroup is illustrated here, other alcohols with allylic chains of varyinglengths (e.g., one to twelve methylene spacer groups) could be used.Additionally, alcohols with acrylate substituents are used in someembodiments.

In process 300-1, the alcohol 305 is reacted with diphenyl phosphite andtitanium isopropoxide (Ti(O^(i)Pr)₄) in benzene to produce a precursor310 to the phosphate-based flame-retardant molecule 240-1. In thispseudo-transesterification reaction, the precursor 310 is formed when aphenyl (Ph) substituent on diphenyl phosphite is replaced by an allyl307 or epoxide 308 R group from the alcohol 305. The precursor 310 isthen reacted with thionyl chloride (SOCl₂) and carbon tetrachloride(CCl₄) over a range of 0° C. to room temperature (RT), forming thephosphate-based flame-retardant molecule 240-1.

In process 300-2, the alcohol 305 is reacted with phenyldichlorophosphate in a tetrahydrofuran (THF) solution containingtriethyl amine (Et₃N). This process is carried out over a range of 0° C.to room temperature (RT). A chloride on the phenyl dichlorophosphate isreplaced by the alcohol 305, forming the phosphate-based flame-retardantmolecule 240-1 with an allyl 307 or epoxide 308 R group.

FIG. 3B is a chemical reaction diagram illustrating two processes 300-3and 300-4 of synthesizing the phosphonate-based flame-retardant molecule240-2, according to embodiments of the present disclosure. In bothprocesses 300-3 and 300-4, an organochloride 320 is a starting materialfor the phosphonate-based flame-retardant molecule 240-2. Theorganochloride has either an allyl R group 307 or an epoxide R group308. It should be noted that, as in the case of the alcohol 305, otherorganochlorides with allylic chains of varying lengths (e.g., one totwelve methylene spacer groups) could be used. Additionally,organochlorides with acrylate substituents are used in some embodiments.

In process 300-3, the organochloride 320 is reacted with triphenylphosphite (P(OPh)₃). The mixture is heated, either by refluxing intoluene or microwaving (mw) in ethanol (EtOH), producing a phosphonylester precursor 325 to the phosphonate-based flame-retardant molecule240-2. The phosphonyl ester precursor 325 is reacted with phosphoruspentachloride (PCl₅) to form the phosphonate-based flame-retardantmolecule 240-2 with an allyl 307 or epoxide 308 R group.

In process 300-4, a mixture of the organochloride 320 and triphenylphosphite (P(OPh)₃) is heated, either by refluxing in toluene ormicrowaving (mw) in ethanol (EtOH), forming a phenylphosphinic acidprecursor 327 to the phosphonate-based flame-retardant molecule 240-2.The reaction is then quenched by raising the pH of the solution. In thisprophetic example, an ethanol (EtOH)/water (H₂O) solution of sodiumhydroxide (NaOH) is added to the reaction mixture. However, in someembodiments, bases other than sodium hydroxide, such as potassiumhydroxide or lithium hydroxide, are used to quench the reaction. Whenthe reaction has been quenched, thionyl chloride (SOCl₂) is added to thephenylphosphinic acid precursor 327, producing the phosphonate-basedflame-retardant molecule 240-2 with an allyl 307 or epoxide 308 R group.

FIG. 3C is a diagrammatic representation of the molecular structures 302of three thiol molecules that are involved in the synthesis of theflame-retardant vanillin-derived molecules, according to someembodiments of the present disclosure. The three thiol molecules are2-mercaptoethanol 335, cysteamine hydrochloride (HCl) 340, and3-mercaptopropionate 345. Each of these thiols is involved in thesynthesis of a thioether-linked flame-retardant vanillin derivative. Thethiol molecules provide a thioether R group. Details of the synthesesand structures of the thioether-linked flame-retardant vanillinderivatives are discussed in greater detail with regard to FIGS. 4B, 4E,and 4H.

FIG. 4A is a chemical reaction diagram illustrating a process 400-1 ofsynthesizing a functionalized flame-retardant phenol vanillin-derivedmolecule 405, according to some embodiments of the present disclosure.In process 400-1, the phenol flame-retardant derivative 215 of vanillinis reacted with a phosphorus-based flame-retardant molecule 240 andcatalytic dimethylaminopyridine (DMAP) in a dichloromethane (DCM)solution. In some embodiments, stoichiometric triethylamine is usedinstead of DMAP. Stirring this mixture yields the functionalizedflame-retardant phenol vanillin-derived molecule 405.

If process 400-1 is carried out with a phosphorus-based flame-retardantmolecule 240 having an allyl R group 307, the functionalizedflame-retardant phenol vanillin-derived molecule 405 will be anallyl-functionalized flame-retardant phenol vanillin-derived molecule405-1. Likewise, if process 400-1 is carried out with a phosphorus-basedflame-retardant molecule 240 having an epoxide R group 308, thefunctionalized flame-retardant phenol vanillin-derived molecule 405 willbe an epoxide-substituted flame-retardant phenol vanillin-derivedmolecule 405-2. If the process is carried out with the phosphate-basedflame-retardant molecule 240-1, the functionalized flame-retardantphenol vanillin-derived molecule 405 will have a phosphoryl FR group,and, if the reaction is carried out with the phosphonate-basedflame-retardant molecule 240-2, the functionalized flame-retardantphenol vanillin-derived molecule 405 will have a phosphonyl FR group.

FIG. 4B is a chemical reaction diagram illustrating three processes400-2, 400-3, and 400-4 of synthesizing thioether-linked flame-retardantphenol vanillin-derived molecules, according to some embodiments of thepresent disclosure. Each process is a thiol-ene reaction between theallyl-functionalized flame-retardant phenol vanillin-derived molecule405-1 and a thiol molecule. The thiol molecules used in processes 400-2,400-3, and 400-4 are 2-mercaptoethanol 335, cysteamine HCl 340, and3-mercaptopropionate 345, respectively. The structures of these thiolmolecules are illustrated in FIG. 3C.

In process 400-2, the allyl-functionalized flame-retardant phenolvanillin-derived molecule 405-1 is reacted with 2-mercaptoethanol 335under UV light. The resulting hydroxyl-functionalized flame-retardantphenol vanillin-derived molecule 410 has a thioether R₃ group 412 thatcorresponds to 2-mercaptoethanol 335. In process 400-3, theallyl-functionalized flame-retardant phenol vanillin-derived molecule405-1 is reacted with cysteamine HCl 340 in a pH 9 methanol (MeOH)solution under UV light. The resulting amino-functionalizedflame-retardant phenol vanillin-derived molecule 415 has a thioether R₄group 417 that corresponds to cysteamine HCl 340. In process 400-4, theallyl-functionalized flame-retardant phenol vanillin-derived molecule405-1 is reacted with 3-mercaptopropionate 345 under UV light in amethanol (MeOH) solution. The resulting carboxylic-acid functionalizedflame-retardant phenol vanillin-derived molecule 420 has a thioether R₅group 422 that corresponds to 3-mercaptopropionate 345.

FIG. 4C is a chemical reaction diagram illustrating a process 400-5 ofsynthesizing a propylene carbonate-functionalized flame-retardant phenolvanillin-derived molecule 425, according to some embodiments of thepresent disclosure. The epoxide-functionalized flame-retardant phenolvanillin-derived molecule 405-2 is combined with lithium bromide (LiBr).Carbon dioxide (CO₂) is added to the mixture, either by injecting itinto the headspace of the reaction flask, or by bubbling it through thesolution. This step yields the propylene carbonate-functionalizedflame-retardant phenol vanillin-derived molecule 425.

FIG. 4D is a chemical reaction diagram illustrating a process 400-6 ofsynthesizing a functionalized flame-retardant carboxylic acidvanillin-derived molecule 430, according to some embodiments of thepresent disclosure. The carboxylic acid flame-retardant derivative 225of vanillin is reacted with a phosphorus-based flame-retardant molecule240, as well as magnesium oxide (MgO) and catalyticdimethylaminopyridine (DMAP). In some embodiments, DMAP is omitted fromthe reaction. Stirring this mixture yields the functionalizedflame-retardant carboxylic acid vanillin-derived molecule 430.

If process 400-6 is carried out with a phosphorus-based flame-retardantmolecule 240 having an allyl R group 307, the functionalized carboxylicacid vanillin-derived molecule 430 will be an allyl-functionalizedflame-retardant carboxylic acid vanillin-derived molecule 430-1.Likewise, if process 400-6 is carried out with a phosphorus-basedflame-retardant molecule 240 having an epoxide R group 308, thefunctionalized carboxylic acid vanillin-derived molecule 430 will be anepoxide-substituted flame-retardant carboxylic acid vanillin-derivedmolecule 430-2. If the process is carried out with the phosphate-basedflame-retardant molecule 240-1, the functionalized flame-retardantcarboxylic acid vanillin-derived molecule 430 will have a phosphoryl FRgroup, and, if the reaction is carried out with the phosphonate-basedflame-retardant molecule 240-2, the functionalized flame-retardantcarboxylic acid vanillin-derived molecule 430 will have a phosphonyl FRgroup.

FIG. 4E is a chemical reaction diagram illustrating three processes400-7, 400-8, and 400-9 of synthesizing thioether-linked flame-retardantcarboxylic acid vanillin-derived molecules, according to someembodiments of the present disclosure. Each process is a thiol-enereaction between the allyl-functionalized flame-retardant carboxylicacid vanillin-derived molecule 430-1 and a thiol molecule. The thiolmolecules used in processes 400-7, 400-8, and 400-9 are2-mercaptoethanol 335, cysteamine HCl 340, and 3-mercaptopropionate 345,respectively. The structures of these thiol molecules are illustrated inFIG. 3C.

In process 400-7, the allyl-functionalized flame-retardant carboxylicacid vanillin-derived molecule 430-1 is reacted with 2-mercaptoethanol335 under UV light. The resulting hydroxyl-functionalizedflame-retardant carboxylic acid vanillin-derived molecule 435 has athioether R₃ group 412 that corresponds to 2-mercaptoethanol 335. Inprocess 400-8, the allyl-functionalized flame-retardant carboxylic acidvanillin-derived molecule 430-1 is reacted with cysteamine HCl 340 in apH 9 methanol (MeOH) solution under UV light. The resultingamino-functionalized flame-retardant carboxylic acid vanillin-derivedmolecule 440 has a thioether R₄ group 417 that corresponds to cysteamineHCl 340. In process 400-9, the allyl-functionalized flame-retardantcarboxylic acid vanillin-derived molecule 430-1 is reacted with3-mercaptopropionate 345 under UV light in a methanol (MeOH) solution.The resulting carboxylic-acid functionalized flame-retardant carboxylicacid vanillin-derived molecule 445 has a thioether R₅ group 422 thatcorresponds to 3-mercaptopropionate 345.

FIG. 4F is a chemical reaction diagram illustrating a process 400-10 ofsynthesizing a propylene carbonate-functionalized flame-retardantcarboxylic acid vanillin-derived molecule 450, according to someembodiments of the present disclosure. The epoxide-functionalizedflame-retardant carboxylic acid vanillin-derived molecule 430-2 iscombined with lithium bromide (LiBr). Carbon dioxide (CO₂) is added tothe mixture, either by injecting into the headspace of the reactionflask, or by bubbling through the solution. The step yields thepropylene carbonate-functionalized flame-retardant carboxylic acidvanillin-derived molecule 450.

FIG. 4G is a chemical reaction diagram illustrating a process 400-11 ofsynthesizing a functionalized flame-retardant benzyl alcoholvanillin-derived molecule 455, according to some embodiments of thepresent disclosure. The benzyl alcohol flame-retardant derivative 235 ofvanillin is reacted with a phosphorus-based flame-retardant molecule 240and catalytic dimethylaminopyridine (DMAP) in a dichloromethane (DCM)solution. In some embodiments, stoichiometric triethylamine is usedinstead of DMAP. Stirring this mixture yields the functionalizedflame-retardant benzyl alcohol vanillin-derived molecule 455.

If process 400-11 is carried out with a phosphorus-based flame-retardantmolecule 240 having an allyl R group 307, the functionalized benzylalcohol vanillin-derived molecule 455 will be an allyl-functionalizedflame-retardant benzyl alcohol vanillin-derived molecule 455-1.Likewise, if process 400-11 is carried out with a phosphorus-basedflame-retardant molecule 240 having an epoxide R group 308, thefunctionalized benzyl alcohol vanillin-derived molecule 455 will be anepoxide-substituted flame-retardant benzyl alcohol vanillin-derivedmolecule 455-2. If the process is carried out with the phosphate-basedflame-retardant molecule 240-1, the functionalized flame-retardantbenzyl alcohol vanillin-derived molecule 455 will have a phosphoryl FRgroup, and, if the reaction is carried out with the phosphonate-basedflame-retardant molecule 240-2, the functionalized flame-retardantbenzyl alcohol vanillin-derived molecule 455 will have a phosphonyl FRgroup.

FIG. 4H is a chemical reaction diagram illustrating three processes400-12, 400-13, and 400-14 of synthesizing thioether-linkedflame-retardant benzyl alcohol vanillin-derived molecules, according tosome embodiments of the present disclosure. Each process is a thiol-enereaction between the allyl-functionalized flame-retardant benzyl alcoholvanillin-derived molecule 455-1 and a thiol molecule. The thiolmolecules used in processes 400-12, 400-13, and 400-14 are2-mercaptoethanol 335, cysteamine HCl 340, and 3-mercaptopropionate 345,respectively. The structures of these thiol molecules are illustrated inFIG. 3C.

In process 400-12, the allyl-functionalized flame-retardant benzylalcohol vanillin-derived molecule 455-1 is reacted with2-mercaptoethanol 335 under UV light. The resultinghydroxyl-functionalized flame-retardant benzyl alcohol vanillin-derivedmolecule 460 has a thioether R₃ group 412 that corresponds to2-mercaptoethanol 335. In process 400-13, the allyl-functionalizedflame-retardant benzyl alcohol vanillin-derived molecule 455-1 isreacted with cysteamine HCl 340 in a pH 9 methanol (MeOH) solution underUV light. The resulting amino-functionalized flame-retardant benzylalcohol vanillin-derived molecule 465 has a thioether R₄ group 417 thatcorresponds to cysteamine HCl 340. In process 400-14, theallyl-functionalized flame-retardant carboxylic acid vanillin-derivedmolecule 455-1 is reacted with 3-mercaptopropionate 345 under UV lightin a methanol (MeOH) solution. The resulting carboxylic-acidfunctionalized flame-retardant benzyl alcohol vanillin-derived molecule470 has a thioether R₅ group 422 that corresponds to3-mercaptopropionate 345.

FIG. 4I is a chemical reaction diagram illustrating a process 400-15 ofsynthesizing a propylene carbonate-functionalized flame-retardant benzylalcohol vanillin-derived molecule 475, according to some embodiments ofthe present disclosure. The epoxide-functionalized flame-retardantbenzyl alcohol vanillin-derived molecule 455-2 is combined with lithiumbromide (LiBr). Carbon dioxide (CO₂) is added to the mixture, either byinjecting into the headspace of the reaction flask, or by bubblingthrough the solution. The reaction yields the propylenecarbonate-functionalized flame-retardant benzyl alcohol vanillin-derivedmolecule 475.

In some embodiments, the processes of forming substitutedflame-retardant vanillin derivatives illustrated in FIGS. 4A, 4D, and 4Gare carried out with a mixture of both the phosphate-based 240-1 and thephosphonate-based 240-2 flame retardant molecules. Carrying outprocesses 400-1, 400-6, and 400-11 with a mixture of the phosphate-240-1and phosphonate-based 240-2 flame retardant molecules can result insubstituted flame-retardant vanillin derivatives with both phosphoryland phosphonyl FR groups. However, in some instances, adding a mixtureof phosphate-240-1 and phosphonate-based 240-2 flame retardant moleculescan result in the production of substituted flame-retardant vanillinderivatives with all phosphoryl or all phosphonyl FR groups.Additionally, adding both phosphate-240-1 and phosphonate-based 240-2flame retardant molecules to the reaction can yield a mixture ofproducts that includes some combination of derivatives with either allphosphoryl or all phosphonyl FR groups and derivatives with bothphosphoryl and phosphonyl FR groups.

The flame-retardant vanillin-derived molecules 104 disclosed herein canbe bound to resins via their R functional groups, impartingflame-retardant properties to the resins. Additionally, the resins canbe polymerized, or used without polymerization in applications such asvarnishes and adhesives. The polymers formed from the resins are alsoflame-retardant, due to the presence of the bound flame-retardantvanillin-derived molecules 104. The flame-retardant polymers and resinscan be used in a number of devices.

One example of a polymer that can be made flame-retardant by theaddition of flame-retardant vanillin-derived molecules 104 ispolycarbonate-acrylonitrile butadiene styrene (PC-ABS), a plastic thatis often used in electronics hardware. Flame-retardant vanillin-derivedmolecules 104 can also be incorporated into polyurethane. Polyurethaneis a versatile polymer used in applications that can include acousticdampening, cushioning, plastics, synthetic fibers, insulation,adhesives, etc. The flame-retardant vanillin-derived molecules 104 canalso be added to adhesives such as bio-adhesives, elastomers,thermoplastics, emulsions, thermosets, etc. Further, materialscontaining the flame-retardant vanillin-derived molecules 104 can beincorporated into various devices with electronic components that caninclude printed circuit boards (PCBs), semiconductors, transistors,optoelectronics, capacitors, resistors, etc.

Resins for printed circuit boards (PCBs) can be made flame-retardant byincorporating flame-retardant vanillin-derived molecules 104. PCBs areelectrical circuits that can be found in most types of electronicdevice, and they support and electronically connect electricalcomponents in the device. PCBs are formed by etching a copper conductivelayer laminated onto an insulating substrate. The insulating substratecan be a laminate comprising a resin and a fiber. Many resins in PCBscontain a polymer, such as an epoxy, a polyurethane, apolyhydroxyurethane, a polycarbonate, a polyester, a polyacrylate, apolyimide, a polyamide, a polyurea, a poly(vinyl-ester), etc.Flame-retardant vanillin-derived vanillin molecules 104 can be bound tothe polymers in the PCB resin in order to prevent the PCB from catchingfire when exposed to high temperature environments or electrical poweroverloads.

It should be noted that, in some embodiments, the compounds describedherein can contain one or more chiral centers. These can include racemicmixtures, diastereomers, enantiomers, and mixtures containing one ormore stereoisomer. Further, the disclosed can encompass racemic forms ofthe compounds in addition to individual stereoisomers, as well asmixtures containing any of these.

The synthetic processes discussed herein and their accompanying drawingsare prophetic examples, and are not limiting; they can vary in reactionconditions, components, methods, etc. In addition, the reactionconditions can optionally be changed over the course of a process. Insome instances, reactions that involve multiple steps can be carried outsequentially, and, in other instances, they can be carried out in onepot. Further, in some embodiments, processes can be added or omittedwhile still remaining within the scope of the disclosure, as will beunderstood by a person of ordinary skill in the art.

What is claimed is:
 1. A bondable flame-retardant vanillin-derivedmolecule with a formula of:

wherein M is a flame-retardant substituent; and wherein FR is aphosphorus-based moiety.
 2. The flame-retardant vanillin-derivedmolecule of claim 1, wherein the M is selected from a group consistingof substituents with formulas of:

wherein FR is a second phosphorus-based moiety; and wherein R is asubstituent selected from a group consisting of an allyl substituent, anepoxide substituent, a propylene carbonate substituent, and a thioethersubstituent.
 3. The flame-retardant vanillin-derived molecule of claim1, wherein the FR is a phosphoryl moiety with a formula of:


4. The flame-retardant vanillin-derived molecule of claim 1, wherein theFR is a phosphonyl moiety with a formula of:


5. The flame-retardant vanillin-derived molecule of claim 2, wherein thethioether substituent is selected from a group consisting of ahydroxyl-functionalized thioether substituent, an amino-functionalizedthioether substituent, and a carboxylic acid-functionalized thioethersubstituent.
 6. The flame-retardant vanillin-derived molecule of claim1, wherein the flame-retardant vanillin-derived molecule is bound to aresin.
 7. The flame-retardant vanillin-derived molecule of claim 1,wherein the flame-retardant vanillin-derived molecule is bound to apolymer.